Material spreader

ABSTRACT

A material spreader for the uniform distribution to the soil or to vegetation of particulate material such as fertilizers, pesticides or seeds. The material spreader comprises a hopper for particulate material adapted to be advanced along a given direction, the hopper including an outlet for discharging the particulate material downwardly, an impeller in association with the outlet for broadcasting the discharged material in a generally radial path surrounding the axis of discharge, and a shroud surrounding the impeller aligned to intersect the path of the broadcast material and to deflect the material downwardly to a region of controlled configuration. The shroud is curved, preferably elliptically in horizontal cross-section and has a width along the direction of advance of the spreader which is less than the width along a direction transverse to the direction of advance. The discharge outlet in the spreader is preferably symmetrically aligned with the impeller so that the material is broadcast in a substantially 360° path around the axis of discharge.

This invention relates to a material spreader device and process. Morespecifically, this invention relates to a material spreader of thebroadcast type used for the distribution of fertilizers, pesticides,seeds or other material in particulate or finely divided form to thesoil or to turf or other vegetation and to a process for thedistribution of such particulate material.

Two types of material spreaders are in widespread use: drop spreaders inwhich the material is discharged by gravity along a path whosedimensions conform to those of the discharge opening of the spreader androtary or broadcast spreaders in which the material is cast out beyondthe spreader to cover a region much wider than the dimensions of thespreader. Drop spreaders are very precise and versatile. They produce acontrolled distribution pattern, a factor of importance in their use inspreading control products such as herbicides. In addition, the patternof distribution of a drop spreader does not vary with particle size ordensity of the particulate material being distributed, as it does in thecase of a rotary spreader. However, drop spreaders are slower to usethan a rotary due to the narrow spreading width. Moreover, dropspreaders frequently produce streaking because it is difficult to avoidgaps or overlaps between successive distribution paths. Finally, thefull width agitator causes a drop spreader to push slightly harder thana rotary and operation in wet turf may be a problem due to low groundclearance.

Rotary spreaders, on the other hand, offer the advantages of speed andease of application due to the wide swath of distribution and the"feathering" at the edges of the distribution pattern. The feathering,or less dense distribution of particulate material at the edges of thepattern, permits overlap between successive paths and thus tolerates acertain amount of error without a streaking problem. Rotary spreaderspush easier than drop spreaders and are better suited to the use ofcorrosion resistant plastic materials. Rotaries also have the advantageof only a few large metering ports for discharge of the particulatematerial rather than a series of small ports, thus accomodating largerparticle sizes. Rotary spreaders have no problems in tall, wet turf. Amajor disadvantage of the rotary spreader is the lack of control of thedistribution pattern. For this reason, rotary spreaders are not normallyrecommended for the distribution of control products or for combinationproducts containing a control product. In addition, rotary spreadersproduce a less uniform distribution pattern than a drop spreader, andthey are susceptible to pattern changes under windy conditions.

An additional disadvantage of a rotary spreader results from thenecessity to spread material in a pattern which is asymmetrical alongthe direction of advance of the rotary spreader. The distributionpattern of a rotary is virtually always asymmetrical front to rear sothat the material will not be thrown on the operator and as an aid inobtaining as uniform a distribution pattern as possible. Theasymmetrical pattern is usually obtained by discharging the materialthrough an outlet in the bottom of the hopper which is off center--usually behind the center of the hopper with respect to its direction oftravel for push-type spreaders, and ahead of the center of the hopperfor pull-type or tractor-mounted spreaders. The specific location of theoffset position of the discharge outlet depends upon the physicalcharacteristics of the particulate material being distributed,particularly its density and particle size. As a result, rotaryspreaders are sensitive to variations in product physicalcharacteristics.

The sensitivity problem with rotary spreaders could be eliminated bydropping material uniformly around or at the center of the impeller. Bydoing so, the distribution pattern would consist of a series ofsuperimposed circles. Such a distribution pattern, however, in additionto throwing the particulate material back on the operator in the case ofa push-type spreader, results in an uneven distribution of particulatematerial containing a band of heavy particle density at the transverseedges of the pattern.

It is accordingly a principal object of the present invention to providea material spreader which combines the advantages of both drop androtary spreaders.

It is an additional object of the present invention to provide amaterial spreader of the rotary or broadcast type which provides bothpattern control and a degree of uniformity of material distributionwhich has not previously been obtainable with rotary spreaders.

It is still an additional object of this invention to provide a materialspreader which possesses the speed and versatility of a rotary spreaderwithout its attendent drawbacks.

It is an additional object of this invention to provide a spreader whichmay be successfully used for the distribution of all types of turfproducts without endangering adjacent non-turf areas.

It is still an additional object of this invention to provide a processfor the uniform and efficient distribution of particulate material tovegetation.

The foregoing and other objects of this invention are achieved by theprovision in a rotary spreader of means for deflecting the broadcastmaterial downwardly to form a pattern of controlled configuration, thedeflection means being generally curved in horizontal cross section andhaving a width along the direction of advance of the spreader which isless than the width along a direction transverse to the direction ofadvance. In its preferred form, the deflection means of the presentinvention is in the form of a shroud, the horizontal cross section ofwhich is substantially in the shape of an ellipse. The ellipticaldistribution pattern produced by such a deflection means produces a 360°distribution pattern, without material build-up at the edges of thepattern, thereby avoiding the necessity for an asymmetrical discharge ofthe particulate material onto the impeller. Thus, the elliptical shroudprovides a desirable distribution pattern using a central drop pointonto the impeller. This eliminates pattern variations resulting fromvariations of the product physical characteristics. Moreover, the shroudpermits the broadcast application of both combination and controlproducts. It retains the advantages of shielding the operator frominclusion within the distribution zone and provides wind protection. Anadditional advantage of an elliptical shroud is that it reduces therequirement for shroud material for a given width of distribution pathas compared with a circular shroud.

Shrouds have been used on agricultural spreaders and on some lawnspreaders for such purposes as wind protection or as stops to limit theextremity of particle distribution. Insofar as is known, however,shrouds for the present purpose or of the present configuration havenever previously been used or disclosed.

The invention will be better understood by reference to the accompanyingdrawing in which:

FIG. 1 is a perspective view of one embodiment of a material spreaderdevice of the invention;

FIG. 2 is a front elevational view of the spreader of FIG. 1;

FIG. 3 is a side elevational view of the spreader of FIG. 1;

FIG. 4 is a cross-sectional view of a portion of the spreader takenalong the lines 4--4 of FIG. 3;

FIG. 5 is a plan view of the shroud as seen along the lines 5--5 of FIG.2;

FIG. 6 illustrates the trajectory pattern obtained by a rotary spreadercontaining a circular shroud in which the particulate material isdischarged centrally onto the impeller;

FIG. 7 illustrates the distribution path obtained during spreader travelwith a spreader having the trajectory pattern of FIG. 6;

FIG. 8 illustrates the trajectory pattern of a rotary spreader with anelliptical shroud in accordance with the invention; and

FIG. 9 illustrates graphically the density of particulate materialacross the width of a distribution path produced in accordance with theinvention.

Referring to the drawing, and particularly FIGS. 1-5, the materialspreader of the invention comprises a hopper 1 for particulate materialsupported by a frame shown generally at 2 mounted on a pair of groundengaging wheels 3. The hopper is illustrated with four discharge portsor outlets 4 at the bottom of the hopper for discharge of particulatematerial to a broadcast means located beneath the hopper. The broadcastmeans comprises an impeller 5 horizontally and fixedly mounted near theupper end of a shaft 6 rotatably driven at the other end thereof by apowered drive connection. The shaft is centrally and equally spaced fromthe four outlets 4 so that the impeller 5 is symmetrically aligned withrespect to the discharge outlets. A handle 7 consisting of two similartubular arms projects from the frame 2 and contains an upper pair ofhandle bars 8 for pushing the spreader.

The frame 2 comprises tubular members 10 and 10' symmetrically mountedat one end thereof on handle 7 and at the other end thereof on two sidepieces 11 and 11'. The side pieces 11 and 11' are in turn connected by acrossbar 12 extending transversely across and beneath the hopper 1. Apair of supports 13 and 13' extend vertically from each of the sidepieces 11 and 11' a portion of the vertical height of the hopper and areattached to the hopper for support thereof. The supports 13 and 13' areoffset slightly, support 13 being slightly behind the center of thehopper support, 13' being the same distance ahead of the center of thehopper. It has been found that least interference with the pattern ofparticulate material occurs when the supports are thus offset. Axle 14is journalled within a pair of frame members 15 and 15' which extendvertically downward from side pieces 11 and 11' respectively, to whichthey are attached. One or both wheels are fixedly connected to axle 14for transmitting power to shaft 6 by means of a bevel gear 16 fixedlymounted on axle 16 in meshing relationship with a smaller bevel gear 17fixedly mounted on vertical shaft 6 at right angles to horizontal bevelgear 16. It will be seen that the wheels are in power drive connectionwith the impeller shaft 6 for rotation of the impeller 5.

The amount of particulate material flowing through discharge outlets 4is metered by adjustment of the size of the outlets. This isaccomplished by a circular closure plate 20 rotatably mounted beneathhopper 1 and shaft 6. Plate 20 contains four holes 21 of the samediameter and spacing as outlets 4 in the hopper. Control rod 22 isattached at one end thereof to a projection 23 on plate 20. The controlrod extends horizontally beyond the hopper, bends from the horizontaland then passes at an angle generally following handle 7 to the upperend of the handle where it is attached to a pivoted lever 24, secured atits pivot point to handle 7. A second projection 25 on plate 20cooperates with an indexed rate plate 26 fixedly secured to the topsurface 32 of the shroud 31. Rate plate 26 has a stop 27 which isslidably adjustable on the plate by, for example, a screw and wing nut.The control rod 22 passes through a guide 28 fixedly mounted on the topsurface 32 of the shroud. A washer 29 is fixedly secured to the controlrod 22. A compression spring 30 contained between fixed guide 28 andwasher 29 acts to bias plate 20 toward rotation in a clockwisedirection. Projection 25 thus rests against stop 27 and locks the platein a preselected position. Adjustment of lever 24 rotates the plate 20approximately 45° from a position in which holes 21 are in completeregistry with outlets 4 to a position in which they are completely outof registry to meter the amount of particulate material passing throughthe discharge outlets.

A shroud or deflection means generally identified at 31 is mountedbeneath hopper 1 and above the impeller 5 on the cross-bar 12 of theframe as by means of attachment bolts (not shown). The shroudillustrated in the drawing is in the shape of a right truncatedelliptical cone, the upper surface of which is closed by a horizontalflat surface 32. The conical surface 33 of the shroud tapers downwardlyand outwardly toward the open end 34, the largest diameter of the shroudthus being at its lower open end thereof. It will be apparent that theshroud may also assume other shapes, as for example, a segment of anellipsoid.

In operation, particulate material flows from the discharge outletsdownwardly and symmetrically about the axis of the impeller. As thespreader is advanced along a given direction, the rotating impellerbroadcasts the particulate material, in a generally horizontal directionin a full 360° circle pattern surrounding the axis of discharge. Theconical surface of the shroud intersects the path of the broadcastmaterial and deflects the material downwardly and outwardly to form aseries of elliptical patterns, overlapping in the direction of advanceof the spreader. Each of the elliptical patterns is feathered to formtransverse edges of lighter density than the remainder of the pattern.Thus, the series of overlapping elliptical patterns forms a continuouspath of particulate material, the density of which is substantiallyuniform along the major central portion thereof but which is of lighterdensity at the edges.

FIGS. 6 through 9 of the drawing illustrate the nature of the improveddistribution pattern obtained in accordance with the invention. Ifparticulate material is discharged symmetrically onto the impeller of arotary spreader with a circular deflection shroud, a trajectory patternof the type shown in FIG. 6 will be obtained. Parallel segments of thispattern of equal width in the direction of spreader travel will be seento have greater particulate density at the transverse edges. This can beseen more clearly in FIG. 7 showing a series of such overlappingcircular patterns formed by a travelling spreader. It will be seen thata particle build-up forming a band of heavy concentration appears at thetransverse edges. This problem is normally avoided by an asymmetricdischarge of the particles onto the impeller to produce only a segmentof a complete circle.

The present invention overcomes the edge-build up problem whilepermitting substantially 360° particle distribution by distributing theparticles in a substantially elliptical pattern. FIG. 8 shows thetrajectory path of the particles in such an elliptical pattern. Thispattern has substantially uniform density along the major centralportion of its width transverse to the direction of travel, with thetransverse edges having a lower density. FIG. 9 illustrates graphicallythe type of particle distribution density actually obtained across thetransverse width of a continuous path produced by a series ofoverlapping elliptical patterns in accordance with the invention.

What is claimed is:
 1. In a spreader for particulate material adaptedfor advance along a given direction having means for discharging saidparticulate material downwardly from said spreader and means inassociation with said discharge means for broadcasting said dischargedmaterial in a generally radial path surrounding the axis of discharge,the improvement comprisingdeflection means surrounding said broadcastmeans tapering downwardly and outwardly, the width of said deflectionmeans along the direction of advance being less than the width along adirection transverse thereto, said deflection means being curved withits radius of curvature being smaller at the transverse end portionsthereof, said deflection means aligned to intersect the path of saidbroadcast material and deflect the material downwardly to form a seriesof patterns of controlled configuration as the spreader is advanced, thedensity of said pattern being substantially uniform along the majorportion thereof, the density along the transverse edges thereof beingless than the major portion.
 2. The material spreader of claim 1 inwhich the deflection means surrounding said broadcast means issubstantially elliptical in horizontal cross-section.
 3. The materialspreader of claim 1 in which the discharge means is symmetricallyaligned with the broadcast means so that the material is broadcast in asubstantially 360° path around the axis of discharge.
 4. The materialspreader of claim 1 in which the deflection means is tapered downwardlyand outwardly such that the region of controlled configuration is wideralong its transverse width than the transverse width of the deflectionmeans.
 5. The material spreader of claim 1 in which the spreadercomprises a wheel supported hopper, said hopper including a centrallydisposed discharge means in the bottom thereof for discharge of meteredamounts of the particulate material and said broadcasting means inassociation with said discharge means being an impeller horizontallymounted beneath the hopper having a powered drive connection with thewheels for rotation as the spreader is advanced, the impeller beingsymmetrically aligned with the discharge means in the hopper forbroadcasting the material in a 360° generally horizontal path.
 6. Thematerial spreader of claim 1 in which the deflection means is atruncated elliptical cone.
 7. The material spreader of claim 1 in whichthe deflection means is a segment of an ellipsoid.